Doorbell system with pulse-driven boost rectifier

ABSTRACT

In some embodiments, a power supply in a doorbell system includes a boost rectifier circuit with a plurality of active devices arranged in a bridge topology that are configured to receive an AC input voltage, generate a DC output voltage by rectifying the AC input voltage, drive an electric load using the rectified DC voltage, and boost an amplitude of the AC input voltage. Two of the plurality of active devices in the boost rectifier circuit may be pulse driven and can control an operation of a mechanical or digital chime device. The chime device can include a solenoid and the boost rectifier circuit may utilize the solenoid as an energy storage element to facilitate the boosting of the amplitude of the AC input voltage. The boost rectifier circuit may boost the AC input voltage by at least a multiplication factor of two.

CROSS REFERENCE PARAGRAPH FOR PRIORITY

This application is continuation of U.S. Non-Provisional applicationSer. No. 16/024,586, filed on Jun. 29, 2018, and titled “DOORBELL SYSTEMWITH PULSE-DRIVEN BOOST RECTIFIER,” which is hereby incorporated byreference in its entirety for all purposes.

BACKGROUND

A doorbell is typically configured as a signaling device placed near adoor to a building's entrance that, when activated, alerts an occupantto the presence of a visitor. Doorbells have existed for over 200 yearswith early versions using mechanical actuators (e.g., pull cords) tostrike a bell plate, and later commercially available models (circa1900) using electrical systems with chimes, bells, or buzzers.Conventional electrically controlled doorbell systems with mechanicalchimes have changed little over the years and still exist in manyhouseholds today.

There have been many technological advances in doorbell systems sincetheir inception. For instance, some doorbell systems may incorporatewireless technology. For example, the doorbell button may contain abattery-powered radio transmitter that sends button state data (e.g., onor off) to a receiver that triggers a chime. Some chimes may bedigitally implemented using a sound chip that plays the sound of a bellthrough a speaker. Some contemporary systems may incorporate a videocamera to provide the user with a visual confirmation of the visitor.

Despite the many advances, many contemporary systems that enhanceexisting doorbell implementations (e.g., adding video capability) needcumbersome add-on supplementary circuitry that is often subject tosignificant power constraints and limited functionality, require trainedtechnicians to test existing systems and properly install the add-oncircuitry, and often require significant doorbell system overhauls thatcan be costly. Better doorbell system designs are needed.

BRIEF SUMMARY

In some embodiments, a power supply in a doorbell system includes adoorbell button and a boost rectifier circuit including a plurality ofactive devices configured in a bridge circuit topology. In response tothe doorbell button (e.g., switch) being deactivated, the boostrectifier circuit can be configured to: receive an alternating current(AC) input voltage, simultaneously rectify and boost the AC inputvoltage thereby generating a direct current (DC) output voltage with ahigher voltage amplitude than the AC input voltage, and drive anelectric load with the boosted and rectified DC voltage. In response tothe doorbell button being activated, the boost rectifier circuit can beconfigured to receive and bypass the AC input voltage. For example,bypassing the AC input voltage can include creating a short ornear-short condition (very low impedance). In some cases, this cansignificantly increase or maximize a current through a bell circuit(mechanical or digital chime device) causing it to ring (activate).

In some cases, the boost rectifier circuit can be configured to becoupled to a mechanical chime device in the doorbell system, themechanical chime device including a solenoid configured to be driven bythe AC input voltage, where the boost rectifier circuit utilizes thesolenoid of the mechanical chime device as an energy storage element tofacilitate the boosting of the amplitude of the AC input voltage, andwhere the boost rectifier circuit bypassing the AC input voltage causesthe mechanical chime device to ring in response to the doorbell switchbeing activated. The boost rectifier circuit may be configured todynamically adjust a boost profile for the boosting of the AC inputvoltage based on an amplitude of the AC input voltage, where the boostprofile pulse shapes an AC current signal driving the solenoid from asinusoidal current waveform to a substantially square-wave currentwaveform (or other suitable current waveform). The pulse shaping of theAC current signal into a square-wave current waveform can cause areduction in a maximum current (e.g., peak current) of the AC currentsignal and a reduction in a transition time between phases of the ACcurrent signal.

In some cases, the at least two of the plurality of active devices inthe boost rectifier circuit can be field-effect transistors (FETs). Thepower supply can further include one or more processors and apulse-width modulator (PWM) circuit controlled by the one or moreprocessors. The PWM circuit can be configured to drive the FETs with apulsed input voltage that controls the boost profile. The PWM circuitcan include a digital-to-analog converter (DAC) controlled by the one ormore processors and a comparator circuit controlled by the one or moreprocessors, where the DAC can dynamically set a current limit thresholdfor the AC current signal passing through the solenoid (solenoidcurrent) based on a current power requirement of the load, where thecomparator can compare the current limit threshold with the solenoidcurrent and generates a corresponding comparator output signal, and thePWM circuit can adjust a duty cycle of the pulsed input voltage based onthe comparator output signal. The boost rectifier circuit can be furtherconfigured to drive a battery charging circuit for a battery systemconfigured to provide power to the electric load. The electric load caninclude a video camera system, audio system, sensor system,communication system, battery charging system (derivative power supplysystem), or the like.

In some embodiments, a method of operating a boost rectifier circuit ofa doorbell system may include receiving, by an input of a boostrectifier circuit, an AC input voltage; simultaneously boosting anamplitude of the AC input voltage and rectifying the AC input voltage,thereby generating a boosted DC output voltage at an output of the boostrectifier circuit; driving an electrical load with the boosted DC outputvoltage; measuring an AC current through a solenoid of a mechanicaldoorbell chime circuit coupled to the input of the boost rectifiercircuit, the solenoid driven by the AC input voltage, and the solenoidoperating as an energy storage element configured to facilitate theboosting of the amplitude of the AC input voltage by the boost rectifiercircuit; and dynamically modifying a boosting profile on the AC inputvoltage based on: the measured AC current in the solenoid; and anamplitude of the AC input voltage. The boost rectifier circuit mayinclude at least four active circuit elements configured in a bridgecircuit topology, and at least two of the four active circuit elementscan be field-effect transistors (FETs) configured to control theboosting profile of the AC input voltage. Other types of active devicescan be used, as further described below.

In some implementations, dynamically modifying the boosting profile ofthe AC input voltage can further include applying a pulsed voltage atinputs of the FETs and generating a charge/discharge ramp for each cycleof the AC input voltage based on the pulsed voltage, wherein thecharge/discharge ramp affects the boosting profile of the AC inputvoltage. In some cases, the charge ramp may correspond to periods oftime when the pulsed voltage is on, the discharge ramp may correspond toperiods of time when the pulsed voltage is off, and a ratio of thecharge-to-discharge periods may define an operational duty cycle for theFETs. The pulsed voltage may be on during each phase of the AC inputvoltage while the measured AC current through the solenoid is below athreshold current value, and the pulsed voltage may be off during eachphase of the AC input voltage while the measured AC current through thesolenoid is at or above the threshold current value. In certainembodiments, the pulse-width modulator applies the pulsed voltage at theinput of the FETs. The electrical load can include a video camerasystem, audio system, sensor system, communication system, batterycharging system (derivative power supply system), or the like.

In further embodiments, a boost rectifier circuit for a doorbell systemcan include a first diode, a second diode, a first field-effecttransistor (FET) and a second FET. In some cases, a drain of the firstFET can be coupled to an anode of the first diode, the drain of thefirst FET can be configured to be coupled to an AC voltage sourcethrough a solenoid of a mechanical doorbell chime circuit, a gate of thefirst FET may be driven by a pulse-width modulator, and a source of thefirst FET can be coupled to an electrical ground through a resistor. Insome cases, a drain of the second FET can be coupled to an anode of thesecond diode, the drain for the second FET can be configured to becoupled to the AC voltage source, a gate of the second FET can be drivenby the pulse-width modulator, a source of the second FET can be coupledto an electrical ground through a resistor, and a cathode of the firstdiode and a cathode of the second diode can be coupled together forminga boost rail node. In some cases, the first diode or the second diodemay be a third FET wherein a source of the third FET is coupled to adrain of the third FET (using body diode characteristics of the FET).The pulse width modulator can be configured to provide a pulsed voltageinput to the first and second FETs causing the first and second FETs toboost an amplitude of an AC input voltage received from the AC voltagesource. The pulsed voltage can be on during each phase of the AC inputvoltage while a measured AC current through the solenoid is below athreshold current value, and the pulsed voltage can be off during eachphase of the AC input voltage while the measured AC current through thesolenoid is at or above the threshold current value.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is set forth with reference to the accompanyingfigures.

FIG. 1 shows a user operating a doorbell system at a residence,according to certain embodiments.

FIG. 2A shows a simplified electrical circuit schematic of aconventional doorbell system.

FIG. 2B shows a simplified electrical circuit schematic of aconventional electronic doorbell system.

FIG. 3 shows a simplified electrical schematic of a mechanical chimecircuit for a doorbell system, according to certain embodiments.

FIG. 4 shows a series of operations during an activation anddeactivation cycle of a mechanical chime circuit, according to certainembodiments.

FIG. 5 shows a simplified electrical schematic of a doorbell systemincorporating a bridge rectifier topology to power a load.

FIG. 6 shows a simplified electrical schematic of a doorbell systemusing a boost rectifier circuit topology, according to certainembodiments.

FIG. 7 shows various performance effects of a mechanical chime inresponse to different current profiles.

FIG. 8 shows solenoid current and electromotive force waveforms for achime device when a doorbell button is pressed.

FIG. 9 shows solenoid current and electromotive force waveforms for achime device in a bridge rectifier-based doorbell system with anelectrical load.

FIG. 10 shows a simplified waveform showing voltage and current for achime device solenoid using a bridge rectifier circuit topology andelectrical load.

FIG. 11 shows solenoid current and electromotive force waveforms for achime device using a boost rectifier circuit topology and electricalload, according to certain embodiments.

FIG. 12 shows a simplified waveform showing voltage and current for achime device solenoid using a boost rectifier circuit topology andelectrical load, according to certain embodiments.

FIG. 13 shows a start-up current waveform for an electric load in adoorbell system using a boost rectifier circuit topology, according tocertain embodiments.

FIG. 14 shows a current limiter and driver system 1400 for a boostrectifier circuit, according to certain embodiments.

FIG. 15 shows an undamped battery charging circuit and correspondingwaveforms for a doorbell system using a boost rectifier circuittopology, according to certain embodiments.

FIG. 16 shows a damped battery charging circuit and correspondingwaveforms for a doorbell system using a boost rectifier circuittopology, according to certain embodiments.

FIG. 17 shows an AC input voltage and solenoid current waveform duringeach phase of a boost rectification operation in a doorbell system,according to certain embodiments.

FIG. 18 shows a “half-cycle A” charge path for a doorbell system,according to certain embodiments.

FIG. 19 shows a “half-cycle A” discharge path for a doorbell system,according to certain embodiments.

FIG. 20 shows a “half-cycle B” charge path for a doorbell system,according to certain embodiments.

FIG. 21 shows a “half-cycle B” discharge path for a doorbell system,according to certain embodiments.

FIG. 22 shows a charge/discharge waveform for a boost rectifier circuitimplemented by a pulse-width-modulator-based drive system during alow-amplitude phase of an AC input voltage, according to certainembodiments.

FIG. 23 shows a charge/discharge waveform for a boost rectifier circuitimplemented by a pulse-width-modulator-based drive system during ahigh-amplitude phase of an AC input voltage, according to certainembodiments.

FIG. 24 shows a changing pulse frequency with respect to a phase of anAC input voltage, according to certain embodiments.

FIG. 25 shows a simplified flowchart showing an operation of a boostrectifier circuit in a doorbell system, according to certainembodiments.

FIG. 26 shows a simplified flowchart showing an operation of a boostrectifier circuit in a doorbell system, according to certainembodiments.

FIG. 27 shows a charge/discharge waveform for a boost rectifier circuitused with a digital chime circuit, according to certain embodiments.

FIG. 28 shows a simplified block diagram of a doorbell system, accordingto certain embodiments.

DETAILED DESCRIPTION

Embodiments of this invention are generally directed to electronicsystems. More specifically, some embodiments relate to an improveddoorbell system using boost rectification to improve power consumptioncharacteristics for wide variety of supplementary doorbell systemmodifications, additions, and other system enhancing applications.

In the following description, for the purpose of explanation, numerousexamples and details are set forth in order to provide an understandingof embodiments of the present invention. It will be evident, however, toone skilled in the art that certain embodiments can be practiced withoutsome of these details, or with modifications or equivalents thereof.

Aspects of the invention relate to a novel boost rectifier circuit thatcan be incorporated into an existing conventional doorbell system in a“plug and play” fashion, such that no additional modifications orcomplicated installations are required. A user can simply replace aconventional button in a doorbell system with boost rectifiercircuit-enabled system (e.g., Wi-Fi enabled video camera system), andthe existing power supply structure can provision a substantiallyincreased power demand of the added load without causing adverseperformance effects in the existing doorbell system, such asinadvertently ringing the doorbell chime while provisioning theincreased load. This is advantageous because no additional wiring orpower supply (e.g., a wall outlet) is needed other than the doorbellpower supply system already in place. Aspects of the invention can beapplied to any conventional doorbell system including systems havingdifferent AC wall voltages (e.g., 110 V, 220 V), different step-downtransformers (e.g., typically 8 V, 16 V, or 24 V), and different chimemechanisms (e.g., mechanical chimes, digital chimes, etc.). In contrast,many contemporary doorbell systems with enhanced functionality (e.g.,video doorbells) often incorporate special add-on circuitry to shunt thechime mechanism, additional power supplies, or other features that oftenrequire industry expertise to properly install and, in many cases, arestill hampered by power limitations.

At a high level of abstraction, aspects of the boost rectifier circuituse a plurality of active devices, such as diodes andfield-effect-transistors (FETs) configured in a bridge-like topology,that takes advantage of a typically high self-inductance of a solenoidin the previously existing mechanical chime circuit and uses it as astorage element to facilitate boosting an AC input voltage (typicallyreceived from an existing step-down transformer) to drive an added load(e.g., a video camera system). Boosting the AC input voltage allows alarger portion of the AC waveform to be used to provision the load.Further, the active devices (also referred to as “active elements”) maybe driven in a manner that pulse shapes the current through the solenoidfrom a sine wave to a square wave or other wave shape, which can reducea peak current through the solenoid, reduce a crest factor of thecurrent, and reduce a transition time between phases (see, e.g., FIGS.11-12), thereby providing more headroom for an increased power drawwithout causing the chime to inadvertently ring. Further, the mechanicaldoorbell switch can be functionally replaced by a voltage control schemaapplied to the active devices of the bridge-like topology, as furtherdiscussed below at least with respect to FIG. 6.

For a more detailed and non-limiting example, some implementations ofsuch novel doorbell systems can include a doorbell button and a boostrectifier circuit having a plurality of active devices configured in abridge circuit topology. In response to the doorbell button beingdeactivated, the boost rectifier circuit can be configured to receive anAC input voltage, simultaneously rectify and boost the AC input voltagethereby generating a direct current (DC) output voltage with a highervoltage amplitude (a “boosted” voltage) than the AC input voltage. Anelectric load (which may be multiple loads) can be driven with theboosted and rectified DC voltage. Some electric loads can include aWi-Fi enabled video camera system, audio system, a battery chargingsystem, or other suitable doorbell system enhancing application. Inresponse to the doorbell switch being activated, the boost rectifiercircuit may be configured to receive and bypass the AC input voltage,which can effectively short two or more of the plurality of activedevices (e.g., field-effect transistors) to create an electricalcondition functionally similar to activating a single-pole, normallyopen (SPNO) mechanical switch in a conventional doorbell system thatcauses the mechanical chime device of the doorbell system to ring.

The boost rectifier circuit can be configured to be coupled to themechanical chime device in the doorbell system to utilize the solenoidof the mechanical chime device as an energy storage element tofacilitate the boosting of the amplitude of the AC input voltage. Theboost rectifier circuit can dynamically adjust a boost profile for theAC input voltage based on an amplitude of the AC input voltage in amanner that causes the AC current signal driving the solenoid to bepulse-shaped from a sinusoidal current waveform to a substantiallysquare-wave current waveform. Certain elements of the boost rectifiercircuit can be pulsed using pulse-width modulator (PWM) circuit toachieve a desired boost profile, as further described below at leastwith respect to FIG. 14. Some advantages to pulse-shaping in this mannerinclude a reduction in a maximum current of the AC current signal and areduction in a transition time between phases of the AC current signal,as shown in FIG. 11-12, which effectively allows more power to be drawnfrom the doorbell circuit without causing the mechanical chime to beactivated (e.g., rung). It should be noted that the precedingdescription is meant as a general overview of certain embodiments of theinvention and does not limit the many variations, modifications, andalternative embodiments contemplated throughout the totality of thisdocument. Further, it should be understood that any of the embodiments,modifications, or the like described herein can be combined in anysuitable manner, as would be appreciated by one of ordinary skill in theart with the benefit of this disclosure.

FIG. 1 shows a user 105 operating a doorbell system 100 at a residence,according to certain embodiments. Doorbell system 100 can typicallyinclude a doorbell button 110, a load (e.g., video camera 120), and achime device (e.g., mechanical chime circuit 130). Doorbell button 110and load 120 typically replace an original doorbell button (e.g., singlepole, normally open or “SPNO” mechanical switch) in an existing doorbellsystem. One advantage of directly coupling to and integrating within anexisting doorbell system is that no additional power supplies and/orunwieldy power cables are needed for operation. The existing powerinfrastructure, which is typically a stepped down voltage sourced froman AC power outlet (e.g., 110 V or 220 V), can operate to both cause thechime device to ring and drive the additional load (e.g., video camera120). A significant challenge, however, is that drawing too much powerwhile provisioning the load may cause the chime device (in series withthe load) to ring. To address this problem, some contemporary systemswith additional loads (e.g., video camera systems) need to addadditional circuitry (e.g., a shunt across the chime device) orincorporate low power applications to prevent an inadvertent ringing ofthe chime device from occurring. In contrast, aspects of the inventionpresent a marked improvement over contemporary designs in that certainembodiments can provide comparatively significant increases in powerdelivery to a load without the need of modifying or adding any newcircuitry to the existing doorbell system infrastructure (e.g., chimedevice, transformer, wiring, etc.), without causing the chime device toinadvertently ring. Thus, a user can simply remove their existingdoorbell (e.g., SPNO button) and replace it with a button plus loadsystem (e.g., a boost rectifier circuit, as described below at leastwith respect to FIGS. 6 and 11-24) in a plug-and-play fashion to makefor a quick and simple installation process.

Referring back to FIG. 1, image 125 can be generated by video camera 120and coupled (e.g., via Wi-Fi) to a Wi-Fi router, hub, computing device(e.g., laptop, smart phone, smart accessory, etc.), or the like, tofacilitate remote viewing, recording, and interaction (e.g., occupantmay communicate with user 105 via Wi-Fi enabled 2-way audio interface).As described herein, the video camera 120 may be the primary load of thedoorbell system. Alternatively or additionally, other loads may beincluded in doorbell system 100 including audio systems, additionalsensor systems (e.g., microphones, motion sensors), communicationsystems (e.g., Wi-Fi, Bluetooth® standards, ZigBee, Z-Wave, infra-red(IR), RF, etc.), lighting systems, control systems, audio systems, orthe like. One of ordinary skill in the art with the benefit of thisdisclosure would understand the many variations, modifications, andalternative embodiments thereof. Although the remainder of thisdisclosure primarily focuses on embodiments incorporating videocapabilities, it should be understood that any suitable load can beincorporated into the embodiments described herein.

FIG. 2A shows a simplified electrical circuit schematic (“circuit”) 200of a conventional doorbell system. Circuit 200 typically includes apower supply (“V1”), transformer 210, bell circuit 220, and actuator 230configured in a series-coupled arrangement, as shown. V1 can be an ACpower supply, which is typically sourced by a local electric utility. Inmost applications, V1 may be approximately 110 V or 220 V. V1 may becoupled to transformer 210, which is typically a step-down transformerthat causes an AC voltage across L1A (e.g., 110V) to step down to alower amplitude AC voltage across L1B (e.g., 8 V, 16 V, 24 V), which maynot pose the risk of an electric shock should a fault occur. Thestepped-down AC voltage across L1B (“Vin”) passes through bell circuit220 and button 230.

Bell circuit 220 can be a chime device. In some cases, bell circuit maybe a mechanical chime device with one or more integrated solenoids(shown as coil L2). The solenoid (typically a large, wound inductor)includes a metal rod and spring that strikes one or more bell plateswhen the solenoid is energized, as further shown and described belowwith respect to FIG. 3. Although the embodiments described hereinlargely include wired, solenoid-based mechanical chime devices, itshould be understood that other types of chime devices including digitalchime devices, wireless chime devices, alternative alert systems (e.g.,intercoms), etc., may be used instead of, or in addition to, thesolenoid-based implementations, as would be appreciated by one ofordinary skill in the art with the benefit of this disclosure.

Actuator 230 (referred to as a “switch” or “button”) may be a mechanicalswitch (typically a normally off momentary pushbutton switch—SPNO) thatopens and closes the series circuit. Any suitable switch type can beused (e.g., mechanical, digital, button, slider, plunger, etc.). Whenactuator 230 is closed (i.e., completes the circuit), AC current flowsthrough L2 (thereby energizing L2), actuator 230, and any other circuitelements (e.g., R3) in the loop. Wiring in circuit 200 typicallyincludes small gauge wiring (commonly referred to as “bell wiring” and“twisted pair”), but any suitable gauged wire may be used. In someembodiments using a boost rectifier circuit, as shown and furtherdescribed below with respect to FIG. 6, a button press may initiate acertain biasing configuration of the boost rectifier circuit that maycause a (near) short circuit condition that effectively has the samefunction as closing a mechanical switch (as shown in FIGS. 2-3). Thus auser would still press a button to ring the bell, but the implementationof the ring would be electronically driven (e.g., by biasingtransistors) rather than mechanically driven (e.g., physically pressinga button) to close the doorbell circuit.

In many of the embodiments that follow (e.g., FIGS. 6 and 11-24), thepower source, transformer, and bell circuit may be similar to thecircuit topology shown in FIG. 2, with the exception that the button isreplaced by a boost rectifier circuit (e.g., FIG. 6) and load (e.g.,button/video camera 110/120 of FIG. 1). This is advantageous as areplacement of a doorbell system with a more advanced doorbell system(e.g., a Wi-Fi enabled video system) may only require a user to replacethe actuator 230 with the new doorbell system for a simple installationthat may not require any modification to the existing doorbell systeminfrastructure (e.g., wiring, transformer, bell circuit, power source.

FIG. 2B shows a simplified electrical circuit schematic (“circuit 250”)of an electronic doorbell system. Circuit 250 can include all of thesame components as circuit 200, but with a digital doorbell system 260instead of a mechanical chime circuit and corresponding solenoid, asdescribed above with respect to circuit 200, and the addition of ashunted “bypass” diode 270. The bypass diode is configured in parallelwith the button (e.g., switch), such that current flows through thedigital bell during one of the half cycles (either A or B), which can bewhen the switch is open and the bypass diode is forward biased (shown asthe solid-lined current path). The digital bell circuit may monitor thecurrent flow in the direction which is normally zero (e.g., switch openwith the bypass diode reverse biased) (shown as the dashed-line currentpath). When the button is depressed, the switch closes thus shorting thediode and increasing the current flow through the circuit. The digitalbell circuit may detect this and start playing a song (e.g., userselectable). The song may continue to play after the button is releasedbecause the digital bell continues to receive power through the bypassdiode in the corresponding non-detection half-cycle. The operation of atypical electronic chime-based doorbell system as shown in FIG. 2B wouldbe appreciated by one of ordinary skill in the art with the benefit ofthis disclosure.

FIG. 3 shows a simplified electrical schematic of a chime system 300 fora doorbell system, according to certain embodiments. Chime system 300may include mechanical chime circuit 320 coupled to a transformerthrough switch 330, similar to the circuit topology shown and describedabove (e.g., transformer 210 and button 230) with respect to FIG. 2.Chime circuit 320 can include a solenoid 324, plunger 328, spring 326,and resonators 322, 323. Plunger 328 (also referred to as a “hammer”) istypically made of metal (e.g., iron or other ferromagnetic material) andmay be configured to move into and out of a core of solenoid 324 inresponse to the presence of an electromagnetic field (e.g., whensolenoid 324 is energized). Plunger 328 may include hammer-like featureson each end to strike resonators 322, 323, however they are notrequired. Spring 326 may be configured in a helicoidal shape and wrappedaround metal rod 328. Resonators 322, 323 (also referred to as “plates”or “chimes”) may be flat metal bars (e.g., copper, brass, steel) orother material that, when struck by the plunger, produces an audiblesound. Resonators 322, 323 are typically tuned to musical notes that canbe configured to generate a two-tone sound (e.g., “ding-dong”). Simpleror more complex arrangements of resonators are possible, includingadditional solenoids, plungers, and/or resonators, to create moresophisticated musical patterns. One of ordinary skill in the art withthe benefit of this disclosure would understand the many variations,modifications, and alternative embodiments thereof.

In operation, when a doorbell is pressed (e.g., switch 330 closes), anAC current provided by the transformer-coupled AC power source (e.g.,110 V AC) flows through solenoid 324), generating a magnetic field. Themagnetic field causes the solenoid's plunger 328 to move throughsolenoid 324 with a high enough force to compress spring 326 and strikeresonator 323 to ring at a first frequency with a sufficiently loudvolume. When the doorbell is released, the magnetic field dissipates anda restoring force of spring 326 pushes the plunger in the oppositedirection with a strong enough force to strike the other resonator 322to ring at a second frequency with a sufficiently loud volume, therebygenerating the “ding-dong” chime. Typically, the plunger is notpolarized and each phase of the AC current (e.g., positive and negativecurrent swings) cause the plunger to move in the same direction towardsthe same resonator. Further, some systems are under-damped to ensurethat the movement of the plunger in either the energized or de-energizedstate can strike each resonator with a sufficient force.

FIG. 4 shows a series of stages (A-H) during an activation anddeactivation cycle of a mechanical chime circuit, according to certainembodiments. The activation cycle can include periods where AC currentpasses through the solenoid (e.g., circuit is closed), corresponding tostages A-D. The deactivation cycle can include periods of time where noAC current is passing through the solenoid (circuit is open),corresponding to stages E-H. At stage A, the mechanical chime circuitcan be idle. Typically, stage A may correspond to a period of no currentflow through the solenoid where enough time has passed such that anymovement has ceased and any vibrations or reverberations havedissipated. At stage B, the button is depressed, a magnetic field isgenerated around the solenoid, causing plunger to begin to acceleratetowards a first resonator. At stage C, because the system is underdamped(e.g., not enough resistance to stop the plunger from moving), theplunger strikes the first resonator causing a first tone in the doorbellchime sequence. At stage D, the plunger bounces off of the resonator,but reaches equilibrium while it remains in the magnetic field.Typically, the point of equilibrium may be close to but not in contactwith the resonator, due to the damping effect. The plunger may continueto vibrate, which may manifest in a continued audible hum if the plungercontinues to make some contact with the resonator. Other sources ofvibration may include 60 cycle hum, as would be appreciated by one ofordinary skill in the art with the benefit of this disclosure.

In the deactivation cycle, when the button is released and AC current isno longer flowing through the solenoid, the plunger may begin toaccelerate back to its idle position (stage E). The acceleration may beprovided by a restoring force in a compressed spring (326) coupled tothe plunger. At stage F, the plunger passes through the idle statelocation due to the restoring force of the spring and the underdampedsystem and strikes the second resonator causing a second tone in thedoorbell chime sequence. At stage G, the plunger bounces off the secondresonator and may oscillate at its natural self-resonant frequency as aresult of the collision. This can be a typical decaying oscillation ofan underdamped “mass, spring, dashpot” system. At stage H, the plungerreturns to the idle state as the force stored in the spring dissipatesand the friction of the underdamped system damps the remainingvibrations.

As described above, some contemporary systems are configured topiggyback on to existing doorbell systems to incorporate additionalfunctionality, such as video capabilities and the like. The challenge isto extract enough power during periods where the doorbell button is notpressed to properly bias and drive the additional systems withoutcausing the doorbell chime device to ring.

Bridge Rectifier-Based Doorbell Systems

In some cases, a bridge rectifier circuit may be incorporated to providefiltered direct current (DC) power to a load (e.g., video system).However, bridge rectifier-based topologies often exhibit sub-optimalperformance characteristics that often result with inadvertent bellringing, bell “buzzing,” insufficient power sourcing (particularly for8V stepdown transformers, which are common in Europe), and otherperformance issues.

FIG. 5 shows a simplified electrical circuit schematic of a doorbellsystem 500 incorporating a bridge rectifier topology to power a load.Doorbell system 500 may include a transformer/power supply 510, a bellcircuit 520, a doorbell button 525 a/b, a bridge rectifier 530, a filter540, and a load 550. Transformer/power supply 510 can include powersupply V1 and transformer L1. Bell circuit 520 may be a mechanical chimedevice, or other suitable chime device (e.g., digital chime, wirelesschime, etc.). For the purposes here, bell circuit is represented byinductor L2, corresponding to an internal solenoid, as described above.Transformer/power supply 510 and bell system 520 may be similar to thepower supply, transformer, and bell systems described above with respectto FIGS. 2-4. Button 525 a/b may be located on the input (525 a) oroutput (525 b) of the bridge rectifier circuit, as shown. When button525 is pressed (in either location), the bridge rectifier, filter, andload are effectively bypassed (e.g. shorted out) thereby maximizing thecurrent passing through the bell circuit and generating a chime. Whenbutton 525 is not pressed, the bridge rectifier, filter, and load arereintroduced back into the circuit. It can be assumed that the operationof doorbell system 500 corresponds to periods of time where the buttonis not pressed.

Bridge rectifier circuit 530 operates to rectify an AC input voltage andgenerate a DC voltage, as would be appreciated by one of ordinary skillin the art with the benefit of this disclosure. Bridge rectifier circuit530 may comprise four diodes D1-D4 configured in a standard full-wavebridge rectifier topology. Filter 540 may include capacitor C1 and/orother circuit elements (typically capacitors, resistors, and inductors)and is typically configured to filter (reduce) voltage ripple present inthe rectified DC voltage. A filter circuit may or may not be present.Load 550 (R_(L)) is shown in a simplified form for the purposes ofexplanation, but may comprise numerous circuit elements and multiplesystems (e.g., audio, video, sensor, additional derived power supplies,etc.).

During operation when the button is not activated, current only flowsthrough the bell circuit 520 (e.g., through solenoid 324) when the ACinput voltage rises above the rectified DC output level (“Vout”) acrossthe load. For example, the AC input voltage may be 16V at L1B (e.g.,assuming a 16 V step down transformer), which is rectified by bridgerectifier 530. The clipped Vout may drive the load and charge one ormore capacitors (e.g., C1) at the output. The load may cause the clippedVout to droop in response to a power requirement. Thus, during instancesnear the peak of a AC input voltage where the AC input voltage is higherthan the voltage at Vout (e.g., the voltage across the bridge rectifier,filter, and load), the bridge diodes may be forward biased causingcurrent to begin flowing through solenoid L2. This rapid change incurrent can manifest as very quick, large current spikes with large deadzones (e.g., periods of no conduction as discussed below with respect toFIGS. 9-10) that can very readily cause the bell circuit toinadvertently chime or buzz as the current flow through the solenoiddirectly corresponds to how much force is applied to the plunger. Asfurther discussed below, the plunger is typically turned on and off at arate of 120 times/sec (60 Hz operation, 2 phases) and increases incurrent draw (via a larger power load) tend to cause a steeper (fasterchange) waveform. Thus, the plunger may lift and fall rapidly inresponse to the current spikes causing the plunger to repeatedly strikethe resonator (e.g., 120 times/sec), resulting in an audible “buzz.” Insome bridge rectifier-based doorbell circuits, this typically occurswith loads drawing approximately 1-1.5 W or less. In some systems, aDC-DC buck converter is used to lower the output voltage and increasethe current through the load, however such systems still suffer from theissues described above. Bridge rectifier-based doorbell systems are notable to operate on systems with 8 V transformers (due to voltagedroops), provide no system control over the bridge voltage, and havelimited power delivery before inadvertently ringing the chime due to thefast/large current spikes and large dead times.

Boost Rectifier-Based Doorbell Systems

FIG. 6 shows a simplified electrical circuit schematic of a doorbellsystem 600 using a boost rectifier circuit topology, according tocertain embodiments. Doorbell system 600 may include a transformer/powersupply 610, a bell circuit 620, an electromagnetic interference (EMI)filter 630, a boost rectifier 660, an output filter 640, and a load 650.Transformer/power supply 610 can include power supply V1 and transformerL1. Bell circuit 520 may be a mechanical chime device, or other suitablechime device (e.g., digital chime, wireless chime, etc.). For thepurposes here, bell circuit is represented by inductor L2, correspondingto an internal solenoid, as described above. Power supply V1,transformer L1, and bell circuit L2 may be similar to the standardtransformer, power supply, and bell circuits described in FIGS. 2-4. TheAC voltage across L1 (V1P to V1N) is typically 8 V, 16 V, or 24 V inmost home doorbell systems. In some cases, additional inductor(s) (e.g.,a high-Q inductor) may be used; particular in embodiments incorporatingdigital chime systems that do not include a solenoid, as shown anddescribed below with respect to FIG. 27. It should be noted that variousnodes (e.g., V1P, V1N, etc.) are included in many of the drawings andwaveforms depicted in the figures and are included to provide a point ofreference for different circuit locations (e.g., V1P is the positiveside of the output of step-down transformer L1, etc.) to provide foreasier reference and context. Such notations in the circuit diagrams(e.g., FIGS. 5, 6, 18-21, 27) and waveforms (e.g., FIGS. 10 and 12)would be understood and appreciated by one of ordinary skill in the artwith the benefit of this disclosure. Although L4 is included in FIG. 6,some embodiments may not include an additional inductor L4 as it is notnecessary to the operation of system 600 or any of the circuittopologies described herein. In some cases, L4 may be an additionalsolenoid found, e.g., in a dual solenoid, dual chime system (e.g.,front/back door doorbell systems).

In some cases, EMI filter 630 may not be included in doorbell system600. EMI filter 630 may be used to minimize radio frequency interferencecaused by the in-house bell circuit wiring acting as an unintentionallong-wave radio antenna at the boost PWM carrier frequency and itsharmonics. The EMI filter may include both series (L1, L3) and commonmode (Lca1, Lcb1) chokes, and a series mode RC snubber (C5, R17). Thisis merely one embodiment of such a filter; many others exist, but a goalremains to minimize radiated emissions to comply with regulatorystandards.

Boost rectifier circuit 660 (also referred to as a “pulse controlledboost rectifier” or “ac/dc boost converter”) may include four activedevices (also referred to as “active circuit elements,” “activecircuits,” “active elements”) including diode D1, diode D2, metal-oxidesemiconductor, field-effect transistor (MOSFET) M1, MOSFET M2, andbiasing resistors R5, R6. The cathodes of D1 and D2 are tied to Vout(e.g., the node across C1 of filter 640 and load 650) forming a “boostrail” node. The anode of D1 may be coupled to the drain of M1 and the apositive output of EMI filter 630 (V3P) or directly to the output ofsolenoid L2 (Vbell) if the EMI filter is not present. The anode of D2may be coupled to the drain of M2 and the negative output of EMI filter630 (V3N) or the negative side of the transformer (V1N) or additionalinductor (VcN). Although M1 and M2 are shown as enhancement-mode MOSFETdevices, depletion-mode MOSFETs, junction gate field-effect transistors(JFETs), p- or n-type bipolar junction transistors (BJTs),insulated-gate bipolar transistors (IGBTs), or other device capable ofswitching the current through the solenoid at a desired PWM frequencymay be used, as would be appreciated by one of ordinary skill in the artwith the benefit of this disclosure. The sources of M1 and M2 may becoupled to a signal and/or electrical ground through one or moreresistors (R5/R6). The gates of M1 and M2 may be coupled to a drivercircuit (e.g., a pulse width modulator), as further discussed below. Insome embodiments, diodes D1 and D2 may be replaced by a FETs. Forexample, an FET has a “body diode” from drain-to-source that can beutilized to function in a similar manner as a discrete diode, as wouldbe appreciated by one of ordinary skill in the art with the benefit ofthis disclosure. Different configurations of resistors, capacitors,and/or inductors may be incorporated at the node occupied by R5 and R6to change biasing characteristics, add filtering effects, or the like,as would be appreciated by one of ordinary skill in the art with thebenefit of this disclosure. For example, R5 may include a series-coupledresistor (e.g., 100Ω) and capacitor (e.g., 1 nF) configured in parallelwith R5. Similarly, R6 may include a series-coupled resistor (e.g.,100Ω) and capacitor (e.g., 1 nF) configured in parallel with R6. Itshould be noted that although specific values of the various componentsare provided in the figures, other component selections may be used, aswould be appreciated by one of ordinary skill in the art with thebenefit of this disclosure.

Filter 640 may include capacitor C1 and/or other circuit elements(typically capacitors, resistors, and inductors) and is typicallyconfigured to filter (reduce) voltage ripple present in the rectified DCvoltage. In some cases, a filter circuit may or may not be present.

Load 650 (R_(L)) is shown in a simplified form for the purposes ofexplanation, but may comprise numerous circuit elements and multiplesystems (e.g., audio systems, video systems, sensor arrays, LEDs (e.g.,IR), auxiliary power supplies, etc.).

In some embodiments, boost rectifier circuit 660 can provide a number ofadvantages and significant performance improvements over systems using astandard bridge rectifier topology (530), which are mentioned here as anoverview and discussed in more detail in the figures that follow. Forinstance, a boost rectifier circuit can both boost and rectify an inputAC voltage using the same circuit elements. Boost rectifier circuit 660typically utilizes an energy storage element, such as an inductor, tofacilitate the boosting of the amplitude of the input AC voltage. Insome exemplary embodiments, boost rectifier circuit 660 advantageouslyuses the self-inductance of the mechanical chime device (e.g., solenoidL2), which can be as high as 7-20 mH or more, as well as self-inductancefrom the bell wires to provide some or all of its energy storage needsto boost the input AC voltage. Using higher inductance values canfurther help boost the input voltage, help reduce switching losses(e.g., switching the operation of M1, M2), and allows for lowerswitching frequencies, which can be easier to control and level, asfurther described below (see, e.g., FIG. 14). Alternatively oradditionally, additional inductors from EMI filter 630 may furtherfunction as energy storage elements during the boost process. Note thatsome embodiments may rectify first and then boost Vin (using differentcircuit elements/topologies unlike system 600), however this has thedisadvantage of delivering less available power to the load.

Boost rectifier circuit 660 can also eliminate the need for a mechanicalswitch (doorbell button), as the circuit topology allows for certainbiasing conditions (e.g., turning on both M1 and M2 through theircorresponding gates) that can perform the same function as a mechanicalbutton in bypassing the additional load and supporting circuitry (e.g.,shorting the vbell and V1N nodes) and causing a sharp increase incurrent through solenoid L2 to cause the bell circuit to chime. Althougha two-tone ring is generally discussed throughout this disclosure, itshould be understood that multi-tone ring patterns are possible (e.g.,ringing resonators in differing patterns) as are chime devices with moresophisticated resonator arrays. For example, a video doorbell withfacial recognition technology might select from several predefined ringpatterns based on the identity of the person at the door. One ofordinary skill in the art with the benefit of this disclosure wouldunderstand the many variations, modifications, and alternativeembodiments thereof and how certain embodiments could be appliedthereto.

In some cases, boost rectification of the input AC voltage has a furtheradvantage of pulse-shaping (e.g., lowering and flattening) the currentthrough solenoid L2 from a sine wave to more of a square-wave shape,which provides the benefit of significantly reducing the peak currentthrough the solenoid (less likely to cause the bell circuit to ring),increasing the amount of total power available to the load, and reducingthe gap between current pulses (e.g., a shortened “dead space”), whichcan result in less plunger travel and vibration and may prevent theplunger from returning and striking the first resonator (323) due to thespring force between current pulses. More power is available to the loadbecause more of the input voltage phase is available to drive the loadin a square wave versus a sine wave, resulting in more energy under thecurve. Recall that power can be extracted with Vin exceeds the boostrectifier output node (M1 and M2 are configured as inverters so thepeaks of Vin occur during the valleys of Vout). Note that power ismeasured as energy per time unit (Watts=Joules/sec). Thus, more energyis available over a longer portion of time of each phase of the AC wavecycle. For instance, low voltage portions of each phase of the AC wavecycle (e.g., 2-5 V) which would be too low to drive current into theload in a standard bridge rectifier circuit due to the reverse biasvoltage of the rectifier diodes, can be boosted to higher voltages(e.g., 40-45 V) in a boost rectified circuit, allowing that portion ofthe AC cycle to provide power to the load, as further described below.

In some embodiments, boosting to a higher voltage may also reduce I²Rpower losses in the solenoid and house wiring because the crest factor(the ratio between peak and rms) of the current is lower. The boostrectifier circuit also allows for precise control over the amount ofboost as well as gradual changes in current (versus steep currentspikes, which are uncontrollable in a standard bridge circuit), whichcan improve battery charging capabilities (e.g., for alkaline,lithium-ion, Ni-Cad, etc., type battery packs) and more control over theoperation of the chime circuit. For instance, in a charging cycle of abattery pack, the boost may be increased accordingly to pull more powerthan needed by the load to simultaneously charge the battery pack. Oncethe battery pack is fully charged, the boost can be lowered to matchaccommodate the load requirement. In a di/dt (change in current)context, a battery system can supplement or replace the load when theload drastically changes (e.g., video is turned off) to avoid a rapidchange in current through solenoid L2. Alternatively or additionally,boost rectifier circuit 660 can gradually or rapidly change the boost tohelp lesson a fast di/dt for solenoid L2, as would be appreciated by oneof ordinary skill in the art with the benefit of this disclosure.Transistors M1, M2 can be biased to emulate a diode across a button(often a complicated install process for a special circuit configured atthe chime location) that is typically needed for doorbell systems withelectronic ringers, such that a maximum power can be pulled by thesystem when needed to cause the bell system to ring when needed.

In operation, transistors M1, M2 can be pulsed (biased) in a manner thatboosts Vout to a higher voltage than Vin (input AC voltage) across thetransformer (e.g., 16 VAC), and maintains Vout at a fixed point withfast switching between voltage phases (e.g., positive and negativeexcursions) to make for a short “dead time.” The dead time may refer tothe period between current pulses in the solenoid that are low enough(e.g., less than 10 mA), such that the spring force overcomes the forceprovided by the electromagnetic field of the solenoid and causes theplunger to strike the resonator. If the dead time is short enough, theplunger will not have enough time to strike the resonator before anotherpositive or negative pulse comes to reintroduce the magnetic field.Transistors M1, M2 may be biased in different ways to achieve thedesired boost voltage. For instance, in some embodiments, M1 may bepulsed during a first half cycle (“phase A”) of the AC input voltage,while M2 is biased on (e.g. continuous voltage applied during phase A),and M2 may be pulsed during a second half cycle (“phase B”) of the ACinput voltage, while M1 is biased on. Different biasing schemes can beused (e.g., for depletion mode MOSFETs), as would be appreciated by oneof ordinary skill in the art with the benefit of this disclosure. Insome implementations, boost rectifier circuit 660 typically boosts Vinto a maximum of approximately 40-45 V, which is typically an upper limitfor bell wiring per the electrical code common to most jurisdictions.

The biasing of each transistor M1, M2 can be implemented via apulse-width modulator (PWM) circuit controlled by a microcontroller(e.g., of system 1400). In some cases, the microcontroller can controlthe AC/DC conversion and boost in real-time (see a further discussionbelow at least with respect to FIGS. 14 and 22-24). The duty cycle ofthe pulses on each of M1, M2 may be partially dependent on Vin vs. Vout.Unlike a typical boost converter circuit (not to be confused with boostrectifier 660), which directly controls/picks a pulsing duty cycle, M1and M2 can be pulsed, in certain embodiments, based on a sensed currentthrough solenoid L2. For instance, the microcontroller can set a currentlimit for the solenoid based, in part, on Vin/Vout and the loadrequirement, and M1/M2 may charge via a pulsed voltage input (Vpulse) intheir corresponding phases (thus boosting Vin), which ramps up thecurrent until the current limit sensed across L2 is reached. When thecurrent limit is reached, M1/M2 may then subsequently turn off, causingthe current to begin ramping down. The microcontroller may then setanother current limit (or maintain a present value) for the next Vpulsebased on Vin/Vout and the load requirement and the charge/dischargecurrent ramp is repeated. This repeated train of charge/discharge rampsmay dictate the shape of the duty cycle of Vpulse (see., e.g., FIGS.22-23). In some cases, the current across L2 can be sensed by measuringa voltage drop across R5 and R6, which may have a similar current asthey are part of the conduction path for each charge/discharge periodfor each phase, as further shown and described below with respect toFIG. 18-21. In some embodiments, the microcontroller may set a currentlimit using a digital-to-analog converter (DAC) and compare a presentcurrent through L2 via a comparator, as shown, e.g., in FIG. 14.

In some embodiments, boost rectifier 660 may slowly ramp up Vout overtime (1-5 s) to prevent a sharp spike in current (e.g., through L2)after the doorbell button is released and avoid ringing the chimecircuit. For instance, while the doorbell button is pushed, boostrectifier 660 may be bypassed to drive solenoid L2 with maximum powerfrom the transformer with no power being applied to the load (notincluding a battery circuit). After releasing the doorbell button, alarge power spike can occur as the boost rectifier circuit beginscharging again to provision the load. In some cases, the power rampingprocess may be gradually increased to prevent a sharp spike, as shownand described below with respect to FIG. 13.

In further embodiments, boost rectifier circuit 660 can be configured toperform diagnostic measurements, self-calibration, and auto-discovery ofa home transformer/wiring infrastructure without needing additionalcircuitry. For example, a smart device (e.g., a smart phone) may be usedonce a boost rectifier-based system is installed to listen (e.g., viamicrophones) to detect if a hum or buzz is present and adjust a currentlimit setting accordingly to mitigate or eliminate it. In some cases, aringing can be determined by detecting changes in the efficiency ofsolenoid L2 caused by eddy currents and/or changes to the inductance andQ factor of L2 as the plunger passes through it. In some cases, acharge/discharge rate on capacitors at the input can be detected and,due to an inductors resistance to changes in current, sharp spikes incurrent may indicate that no inductor is at the input, and thus nosolenoid-based chime circuit is being used (e.g., a digital chime may beused in the doorbell system, as shown and described below with respectto FIG. 27).

As indicated above, FETs have a built-in body diode that cause the FETto operate as a diode when the FET is turned off (not forward biased).Thus, the boost rectifier circuit may be biased to operate as a bridgerectifier when M1 and M2 are turned off. The bridge will stabilize atapproximately Vin (minus forward biasing losses), which can be measuredat Vout to determine what type of step-down transformer is being used(e.g., 8/16/24 V).

Managing Δdi/Δdt in a Chime Device Solenoid

FIG. 7 shows various performance effects of a mechanical chime device inresponse to different current profiles. When there is a sudden change incurrent (Δdi/Δdt), the velocity of the plunger can ramp up and overshootpast the point of equilibrium, thereby striking the bell plate(resonator). However, when there is a gradual change in Δdi/Δdt, boththe velocity and acceleration of the plunger can remain low, such thatthe plunger may not overshoot and thus avoid striking the bell plate.The discussion of FIG. 7 refers to concepts described above with respectto FIGS. 2-4.

To illustrate, when a button is pressed is a typical doorbell system(e.g., doorbell system 200), the electromotive force (or EMF, which isthe energy produced by the interaction between a current and a magneticfield when one (or both) is changing) across inductor L2 may changeimmediately in a step-wise fashion (see 710). In response, the plunger(“hammer”), starting at position A (equilibrium point where spring forceis low and EMF is low), moves very quickly at an increasing velocitythrough the solenoid (see 730) causing the spring force to increase atan increasing rate until the plunger overshoots an equilibrium state,strikes the resonator, bounces off and reaches an equilibrium atposition B (where spring force and EMF is high) when the EMF and springforce are equal (see 720 and 740). Note that the plunger does not moveat equilibrium (other than due to underdamped oscillations).

If the EMF is changed gradually (see 750) across inductor L2 initiallyat position A, the spring force also increases gradually with noovershoot (see 760), the plunger velocity increases slightly andmaintains a low velocity (see 770) until equilibrium at position B isachieved. A similar effect may occur in response to a sudden removal ofEMF. FIG. 7 illustrates how a gradual change in energy through thesolenoid can prevent overshoot, which can help prevent inadvertentringing of the chime circuit when provisioning a quickly changing load.

FIG. 8 shows solenoid current and electromotive force waveforms for achime device when a doorbell button is pressed. Waveform 810 correspondsto a waveform of an electric current through a solenoid, such as L2,when the doorbell button is pressed. Waveform 820 corresponds to an EMFon a plunger (328). Note that the plunger in doorbell circuits aretypically not magnetized, so solenoid current in both positive andnegative excursions cause the plunger to be pulled into the solenoid.

Line 826 may correspond to the point of equilibrium between the EMF onthe plunger and the restoring force provided by the spring. During phaseA (positive excursion) of the current waveform through solenoid L2, theEMF begin accelerating the plunger into the solenoid at region 822. Atregion 824, the spring may begin accelerating the plunger. Note that thepercentage of total time that the spring accelerates the plunger islarge (see plunger motion 830), which ensures that the plunger willovershoot beyond equilibrium (point B, FIG. 7) and strike the resonator.

FIG. 9 shows solenoid current and electromotive force waveforms for achime device in a bridge rectifier-based doorbell system with anelectrical load, such as doorbell system 500 of FIG. 5. Waveform 910corresponds to a waveform of an electric current through solenoid L2 ofsystem 500, when the doorbell button is not pressed and bridge rectifiercircuit 530 is provisioning load 550. Note that the peaks of the ACwaveform (Vin) are clipped to produce power. RMS power, which is thearea under the curve (times the voltage) is very low compared to thepeak current, and thus relatively little power can be generated (e.g.,1-1.5 W or less).

The pulses in waveform 910 can correspond to instances near the peak ofan AC input voltage where the AC input voltage is higher than thevoltage at Vout (e.g., the voltage across the bridge rectifier, filter,and load), and current immediately flows through inductor L2. This rapidchange can manifest as very quick, large current spikes in currentthrough L2 with large dead zones 915 that can very readily cause thebell circuit to inadvertently chime or buzz. The plunger is typicallyturned on and off at a rate of 120 times/sec (60 Hz operation, 2 phases)and increases in current draw (via a larger power load) tend to cause asteeper (faster change) waveform. Thus, the plunger may lift and fallrapidly in response to the current spikes causing the plunger torepeatedly strike the resonator (e.g., 120 times/sec), resulting in anaudible “buzz.” In some bridge rectifier-based doorbell circuits, thistypically occurs with loads drawing approximately 1-1.5 W or less, asmentioned above.

Waveform 920 corresponds to an EMF on the plunger (328). Line 926 maycorrespond to the point of equilibrium between the EMF on the plungerand the restoring force provided by the spring. During phase A of thecurrent waveform corresponding to solenoid L2, the EMF beginsaccelerating the plunger into the solenoid at region 922. At region 924,the spring may begin accelerating the plunger. Note that the percentageof total time (dead time 915) that the spring accelerates the plunger isvery large (see plunger motion 930), which will be highly likely tocause the plunger will overshoot beyond equilibrium (point B, FIG. 7)and strike the resonator.

FIG. 10 shows a simplified waveform showing voltage and current for achime device solenoid using a bridge rectifier circuit topology andelectrical load, such as doorbell system 500 of FIG. 5. V1(v1 p, v1 n)may correspond to the voltage across transformer L1, V2 (v3 p, v3 n) maycorrespond to the voltage at the input of the bridge rectifier, andI(L2) may correspond to the current through solenoid L2. Note the sharp,narrow current spikes corresponding to periods where power is suppliedto the load. The maximum current exceeds 300 mA, although the shortperiods of power delivery limit the total amount of power that can begenerated. As shown in FIG. 10, the effective load can draw 1.34 W givenlow amount of energy under the curve at the input (note—power into thesystem is equal to power out). Note that the large current spikes causethe plunger to move away from the first resonator (position A) at a ratethat will likely overshoot equilibrium (position B) and strike thesecond resonator. Further, the long dead times allow enough time for thespring force to return the plunger to and strike the first resonator aswell. This process may occur at 120 Hz, potentially causing a very loud,constant, buzzing/ringing of the chime circuit while the doorbell buttonis not depressed.

FIG. 11 shows solenoid current and electromotive force waveforms for achime device using a boost rectifier circuit topology and electricalload, such as doorbell system 600, according to certain embodiments.Waveform 1110 corresponds to a waveform of an AC electric currentthrough solenoid L2 of system 600, when the doorbell button is notpressed and boost rectifier circuit 660 is provisioning load 650. Notethat a square wave current provides the most power for a given peakcurrent. The RMS power for the approximate square wave of waveform 1110can be very high as compared to bridge rectifier topologies. Powerdelivered to the load may be as high as 3-4 W or more.

The pulses in waveform 1110 can correspond to periods of time near thepeak of an AC input voltage where the AC input voltage is higher thanthe voltage at Vout (e.g., the voltage across the bridge rectifier,filter, and load), and current flows through inductor L2. Waveform 1120can correspond to an EMF on the plunger (328). Line 1126 may correspondto the point of equilibrium between the EMF on the plunger and therestoring force provided by the spring. During phase A of the currentwaveform corresponding to solenoid L2, the EMF begins accelerating theplunger into the solenoid at region 1122. At region 1124, the spring maybegin accelerating the plunger. Note that the percentage of total time(dead time 1015) that the spring accelerates the plunger is very small(see plunger motion 1130), which will be highly likely to prevent theplunger will overshooting beyond equilibrium (point B, FIG. 7) andstriking the resonator. Thus, the plunger will not have enough time tomove back to position A and can therefore remain suspended between theresonators.

FIG. 12 shows a simplified waveform showing voltage and current for achime device solenoid using a boost rectifier circuit topology andelectrical load, such as doorbell system 600 of FIG. 6, according tocertain embodiments. V1(v1 p, v1 n) may correspond to the voltage acrosstransformer L1, V2 (v3 p, v3 n) may correspond to the voltage at theinput of the bridge rectifier, and I(L2) may correspond to the currentthrough solenoid L2 of system 600 (also referred to as the “inputcurrent” of the system, or IL2). Boost rectification, as describedabove, can facilitate pulse-shaping the current through solenoid L2 intoa square-wave to significantly reduce the maximum current through thechime device solenoid, increase the amount of total power available tothe load, and reduce the gap between current pulses (e.g., less deadspace), which can result in less plunger travel, vibration, and/oreliminate the plunger from striking the resonator due to the springforce between current pulses. More power is available to the loadbecause more of the input voltage phase is available to drive the loadin a square wave versus a sine wave, resulting in more energy under thecurve. This is evident when compared to the solenoid current of a bridgerectified system. At 60 Hz, one phase (e.g., positive phase) of Vin isapproximately 8.3 ms. Referring to FIG. 10, solenoid current L2 does notbegin ramping up until about 3 ms into the first phase. In contrast,FIG. 12 illustrates how solenoid current in L2 in a boost rectifiedsystem begins ramping solenoid current L2 almost immediately (less than0.5 ms) and reaches about half of the maximum current at about 1 ms.Furthermore, the maximum current through L2 is less than 200 mA, ascompared to a peak L2 current in FIG. 10 at over 300 mA. Thus, theplunger moves less. Since L2 current is spread over a longer duration,and power in equals power out, a lower maximum current on L2 and muchhigher output power are attainable (power in=power out).

FIG. 13 shows a start-up current waveform 1300 for an electric load in adoorbell system using a boost rectifier circuit topology, according tocertain embodiments. In some instances, there may be large changes in aload (e.g., a video circuit is enabled or shutoff, a suite of sensorsare powered up, a loudspeaker is powered up, etc.), which my result in alarge change in Δdi/Δdt. In some implementations, AC current in thesolenoid may be ramped up and down slowly (e.g., in a step-wise manner)to manage Δdi/Δdt. Waveform 1300 shows an example of the solenoidcurrent in L2 ramped up at a slow rate, which may extend over any numberof cycles (e.g., 100-500 ms, 1-5 s, etc.). This gradual change in chimecircuit solenoid current can prevent inadvertent ringing of the chimecircuit due to current-induced plunger velocity and overshoot, asillustrated in FIG. 7.

One method of controlling the current through the chime device solenoidis by way of a PWM-based drive system for M1/M2 (see FIG. 6). FIG. 14shows a simplified representation of a current limiter and driver system(“System”) 1400 for a boost rectifier circuit, according to certainembodiments. System 1400 may include a digital-to-analog converter (DAC)1410, a current sense amplifier 1420, a comparator 1430, and a PWM 1440,which drives boost rectifier circuit 1450. In some embodiments, boostrectifier circuit 1450 may correspond to boost rectifier circuit 660 ofFIG. 6. Current sense amplifier 1420 may measure the current throughbias resistors (resistors tied between the source of M1/M2 andelectrical ground) in the boost rectifier circuit 660 of FIG. 6. Asnoted above, and as illustrated in FIGS. 18-21, the current through L2may be the same or substantially the same as the current through R5/R6,so sensing a current through the resistors can effectively provide anaccurate measurement of the current through solenoid L2 (as well asother series-coupled inductance, such as optional high-Q inductor(s)L4).

Ramping the solenoid current (input current) IL2 may occur over longperiods (e.g., 1-5 s when the system is initially powered up and IL2 hassubstantially zero current flow), or shorter period (e.g., 1-100 ms)where IL2 changes due to comparatively smaller changes in a powerrequirement in the load (e.g., night vision IR LEDs are powered on in avideo doorbell system). To control the current through L2, amicrocontroller (or processor) may set DAC 1410 to a low voltage, whichcan be slowly increased over time. Comparator 1430 compares a voltagedrop across R5/R6 (which corresponds to IL2) to the DAC voltage anddrives PWM controller 1440 with the output. Typically, when the voltagedetected across R5 or R6 is less than the DAC voltage, PWM controller1440 can begin charging M1 or M2 of boost rectifier circuit 1450(applying a bias voltage at the gate of M1 or M2). Conversely, when thevoltage detected across R5 or R6 is the same as or greater than the DACvoltage, PWM controller 1440 may stop charging boost rectifier circuit1450 (e.g., removing the bias voltage on the gate of M1/M2). Thestarting and stopping of the output of PWM controller 1440 results in avoltage pulse train on M1/M2 with a duty cycle based, in part, on thesensed current through L2 and Vout/Vin. As mentioned above, the DAC maybe set to incrementally increasing values to ensure that the currentthrough L2 ramps gradually as opposed to sharp spikes, which may causebell circuit ringing or buzzing. The application and removal of thepulsed bias voltage on M1/M2 causes IL2 to ramp up and ramp downaccordingly. This may occur many time during the course of a single ACcycle, as shown and described below with respect to FIG. 22-23, whichultimately affords excellent real-time, high-resolution control of theboost rectification of Vin, the current through L2, the output voltage(Vout).

In some cases, MOSFETs M1/M2 can be turned on and off via PWM controller1440 based on the measure current through L2. During a typical single ACinput cycle, a series of on/off biasing voltages on M1/M2 will manifestas a series of ramp up/ramp down current in L2 (e.g., typically 10-100ramp up/down cycles, although other values are possible). DAC 1410 maybe set based on the load, such that if the load is increasing, DAC 1410may be set incrementally higher, and if the load is decreasing, DAC 1410can be set incrementally lower, thus ensuring gradual changes in IL2, asshown in FIGS. 22-23. Thus, the duty cycle of the biasing (the voltagepulse train) of M1/M2 is modulated as a consequence of the currentlimiting set at the DAC. In some embodiments, a fixed start point and avariable stop point may be set for DAC 1410, such that M1/M2 (e.g., M1during the positive phase of the AC input, and M2 during the negativephase) is driven (IL2 current ramps up) until the current limit isreached, and then it is turned off (IL2 current ramps down). During thenext cycle, a new current limit can be set via DAC 1410, and the processrepeats. Thus, a variable duty cycle results that is controlled inreal-time based on the changing load and the current through L2. Thisprocess may occur hundreds of times for each phase of a single 60 Hzinput cycle. The rate at which the current limit is reached can dependon the voltage being boosted to (Vout) and the AC input voltage (Vin).For instance, the current limit is typically reached faster when Vin ishigh (during maximum excursions in Vin, requiring less boost to reach40-45 V) and slower when Vin is low (when Vin is low), whichpulse-shapes IL2 into a square wave (note that more boosting is need atlow Vin and less boosting is needed at high Vin).

In some embodiments, Vout may be monitored to detect changes in theload, which can be used to modify the current limit set in system 1400.For example, when the load increases, more current may be drawn out ofthe output capacitor C1, which in turn may cause the voltage across C1to droop. In response, the current limit may be increased to providemore power to the load and thereby push Vout back to a target range orvalue (e.g., 40-45 V). When the load decreases, Vout may begin risingand the current limit set by system 1400 may be reduced so less totalenergy is provided at Vout, resulting in a drop in Vout to the targetvalue.

FIG. 15 shows an undamped battery charging circuit and correspondingwaveforms for a doorbell system using a boost rectifier circuittopology, according to certain embodiments. A battery system may beincorporated into boost rectifier circuit 600 as a substitute (orsupplementary) power source that can provision a load when the boostrectifier circuit 660 cannot, such as during a button press when theboost rectifier circuit 660 is bypassed. The battery charging circuit istypically charged by boost rectifier circuit 660. The battery chargingcircuit may draw more power (in additional to the system load) whilecharging its one or more batteries, and less power (or no power) whenthe batteries are fully charged. One goal of some doorbell systems is toisolate the solenoid current from transients that may results from anundamped or underdamped control loop for one or more systems downstreamfrom the solenoid.

Referring to FIG. 15, a sudden increase in the system load (RL) maycause a di/dt event that causes the voltage at node A (Vout) to drop.The battery charger is not damped and may have a fast transient responsethereby increasing its di/dt pushing the voltage back up at node A, andcausing a voltage drop at node B. This, in turn, can cause more currentdraw from the battery charger 1530 (which can have its own controlsystem), which changes dv/dt (point B) of a pre-charger converter system1520, etc., until the cascading fluctuation in di/dt and dv/dt affectsthe current through the solenoid. Note that voltage nodes A, B, and Chave capacitance which reduces the rate of change in voltage. Thesetransients can be further reduced using damped systems, as shown in FIG.16.

FIG. 16 shows a damped battery charging circuit and correspondingwaveforms for a doorbell system using a boost rectifier circuittopology, according to certain embodiments. A sudden increase in thedevice load may cause a di/dt event which, in turn, may cause thevoltage at node A to drop. The battery charger response is damped, sodi/dt ramps more slowly for the voltage at node A to drop, and takesmore time to recover. This transient response propagates up the signalchain (to the left), but each time it is reduced in amplitude andincreased in duration. Additionally, the battery charger can have aprogrammable input current limit which can be set to a low value whilewaiting for a load transient. If node A drops below a threshold, thencurrent can be supplied by the battery. The current limit can then beincrementally increased until it is sufficient to operate the load. Thiswill further reduce the di/dt cascading propagation back to the boostsolenoid. Thus, the boost circuit does not have to react as strongly soa reduced di/dt with a less change in current that is spread overtime ispossible. In some cases, the boost circuit, pre-charger converter,battery charger, or any other systems described herein may be operated,at least in part, by processor(s) 2810.

FIG. 17 shows an AC input voltage and solenoid current waveform duringeach phase of a boost rectification operation in a doorbell system,according to certain embodiments. The boost rectifier circuit 660 isoperated in continuous current mode to generate charge/discharge rampsthrough IL2, as described in the figures that follow. Vin 1720corresponds to the AC input voltage provided by stepdown transformer L1.Positive voltage excursions of Vin are referred to as “Phase A” andnegative voltage excursions are referred to as “Phase B.” Waveform 1710corresponds to the current through L2. The peak of L2 is pulse-shapedinto a square wave and the plateau of the square wave can be comprisedof a high number of charge/discharge ramps, that can more easily be seenin FIGS. 22-23. FIGS. 18 and 19 show a charge/discharge path for Phase Ain a boost rectified system, according to certain embodiments. FIGS.20-21 show a charge/discharge path for Phase B in a boost rectifiedsystem, according to certain embodiments.

FIG. 22 shows a charge/discharge waveform for a boost rectifier circuitimplemented by a pulse-width-modulator-based drive system during alow-amplitude portion of a positive phase of an AC input voltage,according to certain embodiments. A position A in the AC input voltage2210, the voltage is very low on the positive phase swing (e.g., 1-2 Von a 16 Vpk input voltage). Current 2220 (IL2) may be the current in thecharm circuit solenoid of the boost rectifier system 600. Pulse train2230 can be a pulsed voltage input driving M1 and M2 in boost rectifiersystem 600. Each pulse of pulse train 2230 can correspond to a ramp upcharge phase of the boost rectification system where FETs M1/M2 can bebiased on. Periods between pulses (e.g., 0 V or other voltage that doesnot forward bias the gate-to-source of M1/M2) can correspond to rampdown charge phases of the boost rectification system where FETs M1/M2can be biased off.

In some embodiments, the ratio of the ramp up/ramp down waveform (e.g.,the duty cycle) may change through the AC input waveform (Vin). Forexample, when Vin is low (e.g., 0-2 V; point A), the ramp up may have aslow long period, and the ramp down may be fast, as shown in IL2 2220.However, during periods where Vin (2310) is high (e.g., 16V, point B),the ramp up may have a very short period, with a longer ramp downperiod, as shown in FIG. 23. Note that the duty cycle (e.g., 1-Vin/Vout)of pulse train 2230 (e.g., pulse high vs. pulse low) at low Vin valuestends to be greater than 50% and may be closer to 75-80% (or more) nearVin=0-1 V, as a greater boost may be necessary to boost the low Vin to atarget 40-45 V range. In contrast, the duty cycle 2330 of IL2 (2320) athigh Vin values (2310, point B) tends to be less than 50% (e.g., whereVin/Vout approaches 1) and may be closer to 10-20% (or less) nearVin=Vpk (e.g., 16V), as a smaller boost may be necessary to boost therelatively high Vin to a target 40-45 V range. The greater boost at lowVin values and smaller boost at high Vin values results in asquare-shaped current waveform, as shown at least in FIGS. 11-12 and 17.

In traditional DC-DC boost converter systems, the output voltage ismonitored and when Vout drops the current is immediately increased, andwhen Vout rises, the current is immediately increased. The transientresponse in typical DC-DC boost converters is designed to be very fastin this regard in an effort to keep Vout constant. The sudden change incurrent, if applied to doorbell circuit, would have a very highlikelihood of causing the chime device to ring due to the currentspiking. In contrast, in a boost rectifier circuit (e.g., system 600),maintaining a constant Vout is not a primary consideration in the boostrectification process; rather, it is more pertinent to manage the rateof change of input current to prevent inadvertent ringing of the chime,according to certain embodiments of the invention. In some embodiments,as described above, a current limit threshold is set (e.g., via a DAC),and the boost rectification process adapts accordingly (e.g., pulsetrain duty cycle is adjusted). This can result in a slower transientresponse time and more variation in Vout, as compared to a traditionalDC-DC boost converter system.

In some embodiments, the current limit threshold may be set inanticipation of an expected change in the load, rather than justreacting to present changes in the load. For example, a video doorbellsystem with a pulse-drive boost rectification system (e.g., system 600)may be configured to turn on IR emitters at certain times of the daywhen the ambient light falls below a certain level. In such cases, thecurrent limit threshold may begin ramping up over a period of time(e.g., 0.5 s−1 s) to accommodate the greater power requirement of the IRemitters when applied. Note that changes in the load can cause Vout torise or fall, which can cause system 600 to dynamically change thecorresponding boost in the system. By anticipating the change, Vout maybe adjusted so the resulting Vout after the change in load will rise orfall close to the desired output (e.g., 40-45), which can result in amore gradual change in Vout and IL2 to an equilibrium state, which canmitigate any potential current overshoot in IL2. It should be noted thatalthough some of the embodiments described herein depict fixed-sizedon/off pulse cycles, non-fixed pulse cycles may be used. For example, avariable pulse cycle may be useful during long charge periods (e.g.,immediately after the doorbell button is released) for improved boostefficiency as fewer ramp down cycles may be needed to reach a targetcurrent threshold.

FIG. 24 shows a changing pulse frequency with respect to a phase of anAC input voltage, according to certain embodiments. Note that thevariations seen at the top of the square wave of IL2 are a series oframp up/ramp down periods. The PWM duty cycle changes throughout thephase (e.g., phase A) to accommodate the variation of the Vin/Voutratio. During periods of low Vin, the PWM duty cycle is high (e.g., over70%) resulting in a ramp up period that is much longer than the rampdown period. This appears in FIG. 24 as pulses that are very close toone another. At Vin values close to Vpk, the ramp up period may be muchshorter than the ramp down period, resulting in relatively short andsparse pulses. Thus, boost rectification circuit 660 can dynamicallychange a boost amount over each phase of Vin (referred to as a “boostprofile”) in real-time and in a manner that eliminates or greatlyreduces plunger overshoot in the chime circuit and prevents inadvertentringing.

FIG. 25 shows a simplified flow chart 2500 for operating a boostrectifier circuit in a doorbell system, according to certainembodiments. Method 2500 can be performed by processing logic that maycomprise hardware (circuitry, dedicated logic, etc.), software operatingon appropriate hardware (such as a general purpose computing system or adedicated machine), firmware (embedded software), or any combinationthereof. In certain embodiments, method 2500 can be performed by boostrectifier circuit 600, as shown in FIG. 6.

At block 2510, method 2500 can include receiving, by an input of a boostrectifier circuit, an AC input voltage. In some embodiments, AC inputvoltage (Vin) may be supplied by any suitable AC voltage source.Referring to FIG. 6, a wall voltage (e.g., 110/220 V) is stepped downvia transformer (L1) to produce an 8, 16, or 24 V input voltage.

At block 2520, method 2500 can include simultaneously boosting anamplitude of the AC input voltage and rectifying the AC input voltage,thereby generating a boosted DC output voltage at an output of the boostrectifier circuit.

At block 2530, method 2500 can include driving an electrical load RL(650) with the boosted DC output voltage.

At block 2540, method 2500 can include measuring an AC current through asolenoid (L2) of a mechanical doorbell chime circuit coupled to theinput of the boost rectifier circuit. The solenoid may be driven by theAC input voltage. The boost rectification circuit (660) may utilize thesolenoid an energy storage element to facilitate the boosting of theamplitude of the AC input voltage.

At block 2550, method 2500 can include dynamically modifying a boostingprofile on the AC input voltage based on the measured AC current in thesolenoid and an amplitude of the AC input voltage, as further describedabove with respect to FIGS. 6, 11-14, and 17-24.

It should be appreciated that the specific steps illustrated in FIG. 25provide a particular method 2500 for operating a boost rectifier circuitin a doorbell system, according to certain embodiments. Other sequencesof steps may also be performed according to alternative embodiments.Furthermore, additional steps may be added or removed depending on theparticular applications. Any combination of changes can be used and oneof ordinary skill in the art with the benefit of this disclosure wouldunderstand the many variations, modifications, and alternativeembodiments thereof.

For example, some embodiments may additionally or alternatively controlthe type and interval of the ding, dong, buzzing and frequency of thebuzzing. Systems can be programmed via software to make a custom chimesound at the discretion of the user or, when combined with facialrecognition, object detection, device detection, audio detection, orfingerprinting; custom chime patterns can be implemented for differentpeople or objects detected, for example, within a video stream of avideo doorbell system. One of ordinary skill in the art with the benefitof this disclosure would understand the many variations, modifications,and alternative embodiments thereof.

FIG. 26 shows a simplified flowchart showing an operation of a boostrectifier circuit in a doorbell system, according to certainembodiments. Method 2600 can be performed by processing logic that maycomprise hardware (circuitry, dedicated logic, etc.), software operatingon appropriate hardware (such as a general purpose computing system or adedicated machine), firmware (embedded software), or any combinationthereof. In certain embodiments, method 2600 can be performed by system1400, as shown in FIG. 14.

At block 2610, method 2600 can include measuring an AC current through achime device solenoid (L2), according to certain embodiments. In someembodiments, the current can be measured through shunt resistors R5/R6of boost rectification circuit 660. For instance, current through L2 maybe measured across R5 by I=E/R.

At block 2620, method 2600 can include setting a current thresholdthrough solenoid L2. In some embodiments, the current threshold may beset by modifying a voltage setting on DAC 1410 for each charge/dischargecycle, as described above with respect to FIG. 14.

At block 2630, method 2600 can include comparing the measured solenoidcurrent (IL2) to the current threshold. At block 2640, if the solenoidcurrent (IL2) reaches the current threshold, the boost rectificationcircuit 660 stops charging 2650 for that cycle in the charge/dischargecycle (e.g., the ramp down portion begin), as shown and described abovewith respect to FIGS. 22-23. In some cases, the DAC may be reset to anew current threshold value for the next cycle, and method 2600 returnsto block 2620.

At block 2640, method 2600 if the solenoid current (IL2) has not reachthe current threshold (2660), the boost rectification circuit continuescharging 1760 for that cycle in the charge/discharge cycle (e.g., theramp up portion continues in that cycle), and system 1400 continuescomparing the measured current with the current limit (2630).

It should be appreciated that the specific steps illustrated in FIG. 26provide a particular method 2600 for operating a boost rectifier circuitin a doorbell system, according to certain embodiments. Other sequencesof steps may also be performed according to alternative embodiments.Furthermore, additional steps may be added or removed depending on theparticular applications. Any combination of changes can be used and oneof ordinary skill in the art with the benefit of this disclosure wouldunderstand the many variations, modifications, and alternativeembodiments thereof.

Using a Boost Rectifier Circuit with a Digital Chime Circuit

FIG. 27 shows a charge/discharge waveform for a boost rectifier circuit2700 used with a digital chime circuit, according to certainembodiments. Circuit 2700 emulates the operation of bypass diode 270 ofcircuit 250 by keeping one of the NMOS transistors turned on. Forexample, turning on M2 continuously provides the power half-cycle(solid-line current path) and the detection half-cycle (dashed-linecurrent path), as shown in FIG. 27. Such circuit topologies may beadvantageous as no additional cumbersome installations (e.g., a bypassdiode), as they typically are in convention digital doorbell designs, asshown in FIG. 2B.

System for Operating Aspects of a Boost Rectified Circuit

In some embodiments, a boost rectifier circuit may be used to drive anumber of different loads including video camera systems, audio systems,sensor systems, battery charging systems (derivative power supplysystems), or any other systems, and combinations thereof. FIG. 28 is asimplified block diagram of a system 2800 that can be configured tooperate, for instance, a doorbell/camera system using a boost rectifiersystem (600, 2700), according to certain embodiments. System 2800 caninclude processor(s) 2810, camera controller 2820, power managementsystem 2830, communication system 2840, and memory array 2850. Each ofsystem blocks 2820-2850 can be in electrical communication withprocessor(s) 2810. System 2800 may include more or fewer systems, aswould be appreciated by one of ordinary skill in the art, and are notshown or discussed to prevent obfuscation of the novel featuresdescribed herein. System blocks 2820-2850 may be implemented as separatemodules, or alternatively, two or more system blocks may be combined ina single module. For instance, some or all of system blocks 2820-2850may be subsumed by processor(s) 2810. System 2800 and variants thereofcan be used to operate the various rectification circuits described anddepicted throughout this disclosure (e.g., FIGS. 5, 6, 14-16, 18-27). Itshould be understood that references to specific systems when describingaspects of system 2800 are provided for explanatory purposes and shouldnot be interpreted as limiting to any particular embodiment.

In certain embodiments, processor(s) 2810 may include one or moremicroprocessors (μCs) and may control the operation of system 2800.Alternatively, processor(s) 2810 may include one or moremicrocontrollers (MCUs), digital signal processors (DSPs), or the like,with supporting hardware and/or firmware (e.g., memory, programmableI/Os, etc.), as would be appreciated by one of ordinary skill in theart. In some embodiments, processor(s) 2810 may be configured to controlaspects of charging controls, media controls, and the like. Further,processor(s) 2810 may operate aspects of circuits 500, 600, 2700, etc.,such as controlling the operation of the FETs (e.g., controlling the PWMcircuit, as shown in FIG. 14), or any other electrical circuitrydescribed herein, as would be appreciated by one of ordinary skill inthe art with the benefit of this disclosure.

Camera controller 2820 may be configured to control aspects of a modularvideo camera system for any of the embodiments shown and described. Insome aspects, camera controller 2820 may control lens operationsincluding focus control, zoom control, movement control (e.g.,individual movement of the lens), or the like. In some implementations,camera controller 2820 can receive sensor data including ambient visiblelight detection, ambient IR light detection, audio data (e.g., from anon-board microphone), or the like.

In some embodiments, camera controller 2820 can control the imagequality generated by a video camera system 120. For example, the imagequality of still images or video can be reduced (e.g., low-definition)when low-bandwidth conditions exist, and increased (e.g.,high-definition) when high-bandwidth conditions exist. One of ordinaryskill in the art would understand the many variations, modifications,and alternative embodiments thereof.

Memory array 2850 can store information such as camera controlparameters, system control parameters (operations of system 1400),communication parameters, or the like. Memory array 2850 may store oneor more software programs to be executed by processors (e.g.,processor(s) 2810). It should be understood that “software” can refer tosequences of instructions that, when executed by processor(s), causesystem 2800 to perform certain operations of software programs. Theinstructions can be stored as firmware residing in read-only memory(ROM) and/or applications stored in media storage that can be read intomemory for processing by processing devices (processor(s) 2810).Software can be implemented as a single program or a collection ofseparate programs and can be stored in non-volatile storage and copiedin whole or in-part to volatile working memory during program execution.Memory array 2850 can include random access memory (RAM), read-onlymemory (ROM), long term storage (e.g., hard drive, optical drive, etc.),and the like, as would be understood by one of ordinary skill in theart.

Power management system 2830 can be configured to manage powerdistribution between systems (blocks 2810-2850), mode operations, powerefficiency, and the like, for the various modular video camera systemdescribed herein. In some embodiments, power management system 2830 caninclude one or more energy storage devices (e.g., batteries—not shown),a recharging system for the battery (e.g., using a USB cable), powermanagement devices (e.g., voltage regulators), or the like. In certainembodiments, the functions provided by power management system 2830 maybe incorporated into processor(s) 2810. An energy storage device can beany suitable rechargeable energy storage device including, but notlimited to, NiMH, NiCd, lead-acid, lithium-ion, lithium-ion polymer, andthe like. Energy storage devices may be recharged via a cable (e.g., USBcable, data cable, dedicated power supply cable, etc.), or inductivepower coupling.

Communication system 2840 can be configured to provide wired (e.g., viaa power/data cable) and/or wireless communication between camera system300 and one or more external computing devices, peripheral devices,remote servers, local or remotely located routing devices, or the like.Some non-limiting examples of communication between camera mountingdevice and an external computing device can include camera controloperations, communicating status updates including memory capacity andusage, operational properties (e.g., camera specifications, mode ofoperation, etc.) and the like. Communications system 2840 can beconfigured to provide radio-frequency (RF), Bluetooth, infra-red,ZigBee, or other suitable communication protocol to communicate withother computing devices. In some embodiments, a data cable can be a USBcable, FireWire cable, or other cable to enable bi-directionalelectronic communication between video camera system 300 and an externalcomputing device. Some embodiments may utilize different types of cablesor connection protocol standards to establish hardwired or wirelesscommunication with other entities.

Although certain necessary systems may not expressly discussed, theyshould be considered as part of system 2800, as would be understood byone of ordinary skill in the art. For example, system 2800 may include abus system to transfer power and/or data to and from the differentsystems therein.

It should be appreciated that system 2800 is illustrative and thatvariations and modifications are possible. System 2800 can have othercapabilities not specifically described herein. Further, while system2800 is described with reference to particular blocks (2810-2850), it isto be understood that these blocks are defined for convenience ofdescription and are not intended to imply a particular physicalarrangement of component parts. Further, the blocks need not correspondto physically distinct components. Blocks can be configured to performvarious operations, e.g., by programming a processor or providingappropriate control circuitry, and various blocks may or may not bereconfigurable depending on how the initial configuration is obtained.

The following embodiments (as are the embodiments preceding thisparagraph) are supported by the entirety of the description above andcan incorporate elements from any combination of embodiments shown ornot shown (but described) with respect to the figures. In someembodiments, a method of operating a boost rectifier circuit of adoorbell system includes receiving measurement data corresponding to ameasurement of an AC current signal driving an inductor of the doorbellsystem, the inductor coupled to an input of the boost rectifier circuit,wherein the inductor is driven by an AC input voltage, and wherein theinductor is operating as an energy storage element configured tofacilitate the boosting of an amplitude of the AC input voltage by theboost rectifier circuit. The method can further include dynamicallymodifying a boosting profile of the AC input voltage based on: themeasured AC current signal passing through the inductor; and anamplitude of the AC input voltage, wherein the boosting profile pulseshapes the AC current signal driving the inductor from a sinusoidalcurrent waveform to a substantially square-wave current waveform.

In some aspects, the pulse shaping of the AC current signal into asquare-wave current waveform causes a reduction in a maximum current ofthe AC current signal and a reduction in a transition time between peaksof different phases of the AC current signal. Dynamically modifying theboosting profile of the AC input voltage can further include: applying apulsed voltage at inputs of the boost rectifier circuit; and generatinga charge/discharge ramp for each cycle of the AC input voltage based onthe pulsed voltage, wherein the charge/discharge ramp affects theboosting profile of the AC input voltage. The charge ramp can correspondto periods of time when the pulsed voltage is on, wherein the dischargeramp can correspond to periods of time when the pulsed voltage is off,and wherein a ratio of the charge-to-discharge periods defines anoperational duty cycle for the boost rectifier circuit. In some cases,the pulsed voltage is on during each phase of the AC input voltage whilethe measured AC current signal through the inductor is below a thresholdcurrent value, and the pulsed voltage is off during each phase of the ACinput voltage while the measured AC current signal driving the inductoris at or above the threshold current value.

In some embodiments, a pulse-width modulator (PWM) circuit controlled byone or more processors can be configured to apply the pulsed voltage atthe input of the boost rectifier circuit. The method can further includedynamically setting a current limit threshold for the AC current signalbased on a current power requirement of a system load; comparing thecurrent limit threshold with the AC current signal; generating acorresponding comparator output signal; and adjusting the duty cycle ofthe pulsed input voltage based on the comparator output signal. Incertain embodiments, a digital-to-analog converter (DAC) may perform thedynamically setting the current limit threshold, a comparator circuitmay perform the comparing the current limit threshold with the ACcurrent signal and generates the corresponding comparator output signal,and the PWM circuit may perform the adjusting the duty cycle of thepulsed input voltage based on the comparator output signal. The boostrectifier circuit can be configured to drive a battery charging circuitfor a battery system configured to provide power to an electric load. Insome implementations, the inductor may be a solenoid of a doorbell chimecircuit of the doorbell system.

In certain embodiments, a doorbell system comprises: one or moreprocessors; and one or more non-transitory computer-readable storagemediums that include instructions configured to cause one or moreprocessors to perform operations including: receiving measurement datacorresponding to a measurement of an AC current signal driving aninductor of the doorbell system, the inductor coupled to an input of aboost rectifier circuit, wherein the inductor is driven by an AC inputvoltage, and wherein the inductor is operating as an energy storageelement configured to facilitate the boosting of an amplitude of the ACinput voltage by the boost rectifier circuit; and dynamically modifyinga boosting profile of the AC input voltage based on: the measured ACcurrent signal passing through the inductor; and an amplitude of the ACinput voltage, wherein the boosting profile pulse shapes the AC currentsignal driving the inductor from a sinusoidal current waveform to asubstantially square-wave current waveform. In some aspects, the pulseshaping of the AC current signal into a square-wave current waveformcauses a reduction in a maximum current of the AC current signal and areduction in a transition time between peaks of different phases of theAC current signal.

In some implementations, dynamically modifying the boosting profile ofthe AC input voltage further includes: applying a pulsed voltage atinputs of the boost rectifier circuit; and generating a charge/dischargeramp for each cycle of the AC input voltage based on the pulsed voltage,wherein the charge/discharge ramp affects the boosting profile of the ACinput voltage. The charge ramp may correspond to periods of time whenthe pulsed voltage is on, wherein the discharge ramp may correspond toperiods of time when the pulsed voltage is off, and wherein a ratio ofthe charge-to-discharge periods defines an operational duty cycle forthe boost rectifier circuit. In some cases, the pulsed voltage is onduring each phase of the AC input voltage while the measured AC currentsignal through the inductor is below a threshold current value, and thepulsed voltage can be off during each phase of the AC input voltagewhile the measured AC current signal driving the inductor is at or abovethe threshold current value.

In some embodiments, a pulse-width modulator (PWM) circuit controlled byone or more processors may apply the pulsed voltage at the input of theboost rectifier circuit. In some implementations, the one or morenon-transitory computer-readable storage mediums further includeinstructions configured to cause one or more processors to performoperations including: dynamically setting a current limit threshold forthe AC current signal based on a current power requirement of a systemload; comparing the current limit threshold with the AC current signal;generating a corresponding comparator output signal; and adjusting theduty cycle of the pulsed input voltage based on the comparator outputsignal. In some cases, a digital-to-analog converter (DAC) performs thedynamically setting the current limit threshold, wherein a comparatorcircuit performs the comparing the current limit threshold with the ACcurrent signal and generates the corresponding comparator output signal,and wherein the PWM circuit performs the adjusting the duty cycle of thepulsed input voltage based on the comparator output signal. The boostrectifier circuit can be configured to drive a battery charging circuitfor a battery system configured to provide power to an electric load. Incertain embodiments, the inductor is a solenoid of a doorbell chimecircuit of the doorbell system.

The specification and drawings are, accordingly, to be regarded in anillustrative rather than a restrictive sense. It will, however, beevident that various modifications and changes may be made thereuntowithout departing from the broader spirit and scope of the disclosure asset forth in the claims.

Other variations are within the spirit of the present disclosure. Thus,while the disclosed techniques are susceptible to various modificationsand alternative constructions, certain illustrated embodiments thereofare shown in the drawings and have been described above in detail. Itshould be understood, however, that there is no intention to limit thedisclosure to the specific form or forms disclosed, but on the contrary,the intention is to cover all modifications, alternative constructionsand equivalents falling within the spirit and scope of the disclosure,as defined in the appended claims.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the disclosed embodiments (especially in thecontext of the following claims) are to be construed to cover both thesingular and the plural, unless otherwise indicated herein or clearlycontradicted by context. The terms “comprising,” “having,” “including,”and “containing” are to be construed as open-ended terms (i.e., meaning“including, but not limited to,”) unless otherwise noted. The term“connected” is to be construed as partly or wholly contained within,attached to, or joined together, even if there is something intervening.The phrase “based on” should be understood to be open-ended, and notlimiting in any way, and is intended to be interpreted or otherwise readas “based at least in part on,” where appropriate. Recitation of rangesof values herein are merely intended to serve as a shorthand method ofreferring individually to each separate value falling within the range,unless otherwise indicated herein, and each separate value isincorporated into the specification as if it were individually recitedherein. All methods described herein can be performed in any suitableorder unless otherwise indicated herein or otherwise clearlycontradicted by context. The use of any and all examples, or exemplarylanguage (e.g., “such as”) provided herein, is intended merely to betterilluminate embodiments of the disclosure and does not pose a limitationon the scope of the disclosure unless otherwise claimed. No language inthe specification should be construed as indicating any non-claimedelement as essential to the practice of the disclosure.

Preferred embodiments of this disclosure are described herein, includingthe best mode known to the inventors for carrying out the disclosure.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the disclosure to be practicedotherwise than as specifically described herein. Accordingly, thisdisclosure includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the disclosure unlessotherwise indicated herein or otherwise clearly contradicted by context.

The invention claimed is:
 1. A method of operating a boost rectifiercircuit of a doorbell system, the method comprising: receivingmeasurement data corresponding to a measurement of an AC current signaldriving an inductor of the doorbell system, the inductor coupled to aninput of the boost rectifier circuit, wherein the inductor is driven byan AC input voltage, and wherein the inductor is operating as an energystorage element configured to facilitate the boosting of an amplitude ofthe AC input voltage by the boost rectifier circuit; and dynamicallymodifying a boosting profile of the AC input voltage based on: themeasured AC current signal passing through the inductor; and anamplitude of the AC input voltage, wherein the boosting profile pulseshapes the AC current signal driving the inductor from a sinusoidalcurrent waveform to a substantially square-wave current waveform.
 2. Themethod of claim 1 wherein the pulse shaping of the AC current signalinto a square-wave current waveform causes a reduction in a maximumcurrent of the AC current signal and a reduction in a transition timebetween peaks of different phases of the AC current signal.
 3. Themethod of claim 2 wherein dynamically modifying the boosting profile ofthe AC input voltage further includes: applying a pulsed voltage atinputs of the boost rectifier circuit; and generating a charge/dischargeramp for each cycle of the AC input voltage based on the pulsed voltage,wherein the charge/discharge ramp affects the boosting profile of the ACinput voltage.
 4. The method of claim 3 wherein the charge rampcorresponds to periods of time when the pulsed voltage is on, whereinthe discharge ramp corresponds to periods of time when the pulsedvoltage is off, and wherein a ratio of charge-to-discharge periodsdefines an operational duty cycle for the boost rectifier circuit. 5.The method of claim 4 wherein the pulsed voltage is on during each phaseof the AC input voltage while the measured AC current signal through theinductor is below a threshold current value, and wherein the pulsedvoltage is off during each phase of the AC input voltage while themeasured AC current signal driving the inductor is at or above thethreshold current value.
 6. The method of claim 4 wherein a pulse-widthmodulator (PWM) circuit controlled by one or more processors applies thepulsed voltage at the input of the boost rectifier circuit.
 7. Themethod of claim 6 further comprising: dynamically setting a currentlimit threshold for the AC current signal based on a current powerrequirement of a system load; comparing the current limit threshold withthe AC current signal; generating a corresponding comparator outputsignal; and adjusting the duty cycle of the pulsed input voltage basedon the comparator output signal.
 8. The method of claim 7 wherein adigital-to-analog converter (DAC) performs the dynamically setting thecurrent limit threshold, wherein a comparator circuit performs thecomparing the current limit threshold with the AC current signal andgenerates the corresponding comparator output signal, and wherein thePWM circuit performs the adjusting the duty cycle of the pulsed inputvoltage based on the comparator output signal.
 9. The method of claim 1wherein the boost rectifier circuit is configured to drive a batterycharging circuit for a battery system configured to provide power to anelectric load.
 10. The method of claim 1 wherein the inductor is asolenoid of a doorbell chime circuit of the doorbell system.
 11. Adoorbell system comprising: one or more processors; and one or morenon-transitory computer-readable storage mediums that includeinstructions configured to cause one or more processors to performoperations including: receiving measurement data corresponding to ameasurement of an AC current signal driving an inductor of the doorbellsystem, the inductor coupled to an input of a boost rectifier circuit,wherein the inductor is driven by an AC input voltage, and wherein theinductor is operating as an energy storage element configured tofacilitate the boosting of an amplitude of the AC input voltage by theboost rectifier circuit; and dynamically modifying a boosting profile ofthe AC input voltage based on: the measured AC current signal passingthrough the inductor; and an amplitude of the AC input voltage, whereinthe boosting profile pulse shapes the AC current signal driving theinductor from a sinusoidal current waveform to a substantiallysquare-wave current waveform.
 12. The doorbell system of claim 11wherein the pulse shaping of the AC current signal into a square-wavecurrent waveform causes a reduction in a maximum current of the ACcurrent signal and a reduction in a transition time between peaks ofdifferent phases of the AC current signal.
 13. The doorbell system ofclaim 12 wherein dynamically modifying the boosting profile of the ACinput voltage further includes: applying a pulsed voltage at inputs ofthe boost rectifier circuit; and generating a charge/discharge ramp foreach cycle of the AC input voltage based on the pulsed voltage, whereinthe charge/discharge ramp affects the boosting profile of the AC inputvoltage.
 14. The doorbell system of claim 13 wherein the charge rampcorresponds to periods of time when the pulsed voltage is on, whereinthe discharge ramp corresponds to periods of time when the pulsedvoltage is off, and wherein a ratio of charge-to-discharge periodsdefines an operational duty cycle for the boost rectifier circuit. 15.The doorbell system of claim 14 wherein the pulsed voltage is on duringeach phase of the AC input voltage while the measured AC current signalthrough the inductor is below a threshold current value, and wherein thepulsed voltage is off during each phase of the AC input voltage whilethe measured AC current signal driving the inductor is at or above thethreshold current value.
 16. The doorbell system of claim 14 wherein apulse-width modulator (PWM) circuit controlled by one or more processorsapplies the pulsed voltage at the input of the boost rectifier circuit.17. The doorbell system of claim 16 wherein the one or morenon-transitory computer-readable storage mediums further includeinstructions configured to cause one or more processors to performoperations including: dynamically setting a current limit threshold forthe AC current signal based on a current power requirement of a systemload; comparing the current limit threshold with the AC current signal;generating a corresponding comparator output signal; and adjusting theduty cycle of the pulsed input voltage based on the comparator outputsignal.
 18. The doorbell system of claim 17 wherein a digital-to-analogconverter (DAC) performs the dynamically setting the current limitthreshold, wherein a comparator circuit performs the comparing thecurrent limit threshold with the AC current signal and generates thecorresponding comparator output signal, and wherein the PWM circuitperforms the adjusting the duty cycle of the pulsed input voltage basedon the comparator output signal.
 19. The doorbell system of claim 11wherein the boost rectifier circuit is configured to drive a batterycharging circuit for a battery system configured to provide power to anelectric load.
 20. The doorbell system of claim 11 wherein the inductoris a solenoid of a doorbell chime circuit of the doorbell system.